1. Field of the Invention
This invention relates to a high intensity infra-red pyrotechnic decoy flare and in particular to a decoy flare which can be aircraft launched to lure incoming missiles with infra-red seeker systems away from the aircraft exhaust which is itself an infra-red source.
2. Discussion of Prior Art
Known decoy flares conventionally comprise mixtures of fine particulate oxidisable and oxidising materials which undergo pyrotechnic reactions on ignition and which are bound together with an organic binder and pressed to form pellets. Examples of oxidisable materials are oxidisable metals, in particular magnesium and alloys thereof and examples of oxidising materials are oxidising halogenated polymers, in particular polytetrafluoroethylene (hereafter PTFE). When an incoming missile is detected by an aircraft a pellet is launched from the aircraft and is ignited as it is launched. The pellet burns over its surface to produce an infra-red source more intense than the aircraft's exhaust. If the incoming missile has an infra-red seeker system then the missile can be lured away from the aircraft exhaust to the more intensely burning pellet which falls quickly away from the aircraft.
Decoy flares can only lure a seeker system from an aircraft exhaust if the infra-red intensity of the burning pellet is greater than that of the aircraft exhaust. The velocity of the aircraft is limited if the decoy flare is to be effective because as the aircraft velocity increases the reheat of the aircraft's engines increases and the infra-red intensity of the exhaust increases. Conventional decoy flares are not able to protect an aircraft near to the maximum reheat value of its engines. This limit on the aircraft velocity is a disadvantage because it extends the time it takes an aircraft to leave a hostile region and it limits the velocity at which the aircraft can manoeuvre away from an incoming missile.
A known method of enhancing the decoy effect of conventional decoy flares is to launch two or more pellets in quick succession in order to confuse the missile seeker system with further infra-red sources. However such decoys are still not able to protect an aircraft near to the maxim reheat of its engines.